The proposed research is concerned with the sensory response of the skin to vibratory stimuli. The project will examine both simple and complex cutaneous pattern perception. Complex vibratory patterns will be generated by means of a 10 x 10 array of vibrators and by means of the Optacon, a reading machine for the blind. Patterns to be transmitted to the skin will include letters of the alphabet as well as novel patterns. Measures of Ss' performance such as response time and percent correct on pictorial displays will be compared with measures of Ss' performance on abstract displays generated by the same stimulus patterns. Ss' ability to identify patterns presented to the torso will be compared with pattern perception on the fingers. The role of self-generated movement and active vs. passive feedback will also be examined. The less complex patterns will involve psychophysical measures of spatial interaction on the skin such as the masked threshold, difference threshold for intensity, and spatial summation. The effect on these measures of the manipulation of such parameters as the number of sites of masking vibration, the distance among sites of stimulation, the locus of the sites of stimulation, and contactor area will be examined. The adequacy of a proposed additive model for predicting difference and masked thresholds will be tested. BIBLIOGRAPHIC REFERENCE: Craig, J.C. Attenuation of Vibrotactile spatial summation. Sensory Processes, 1976, In Press.